1. Field of the Invention
The present invention relates generally to a drying system and a drying method. More specifically, the invention relates to a drying system and method for removing water adhering to the surface of a cleaned object to be treated, such as a semiconductor wafer or a glass substrate for a LCD.
2. Description of Related Background Art
Generally, in a process for producing semiconductor wafers or the like, there is widely adopted a cleaning method for subsequently immersing and cleaning objects to be treated, such as semiconductor wafers or glass substrates for LCDs (which will be hereinafter referred to as "wafers"), in a cleaning solution, such as a chemical or rinsing solution (pure water), stored in a processing bath.
In such a cleaning treatment, there are adopted (1) a so-called IPA drying method for contacting the surfaces of the cleaned wafers with a dry gas of a volatile organic solvent vapor, such as isopropyl alcohol (IPA) vapor, and for condensing or absorbing the vapor of the dry gas to remove water adhering to the surfaces of the wafers to dry the wafers, (2) a spin drier drying method for rotating wafers at high speed while maintaining the wafers in a horizontal state, and (3) a drying method for spraying a dry gas, e.g., nitrogen (N.sub.2) gas, directly on the surfaces of the wafers to dry the wafers.
However, in the IPA drying method (1), it is feared that the treatment of IPA is in danger since IPA has a high volatility. In addition, since it is required to raise temperature to a high temperature to generate IPA vapor, there are problems in that attention must be paid to temperature control and a large-scale facility must be provided. In the spin drier drying method (2), since the wafers are rotated to utilize centrifugal force to dry the wafers, there is a problem in that water marks are easily made on the wafers to deteriorate the yields. In the drying method (3) for spraying a gas, such as N.sub.2 gas, directly on the surfaces of the wafers, since N.sub.2 gas is sprayed from the outside of the outer peripheries of the wafers, there is a problem in that the non-uniformity in drying is easily caused to deteriorate the yields.